Hydrogen peroxide



Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE,

HYDROGEN PEROXIDE Ernst Berl, Pittsburgh, Pa., assignor to The Mathieson Alkali Works, Inc., a corporation of Virginla No Drawing. Application June 1, 1935,

' Serial N0. 24,585

3 Claims.

(upon which United States Patent 2,000,815 was granted on May 7, 1935) and Serial No. 751,031 filed Nov. 1, 1934, for example. Briefly, the aforementioned prior applications describe operations involving the production of. hydrogen peroxide in an electrolytic cell having a cathode containing activated carbon by reaction between oxygen absorbed by the carbon and cathodic hydrogen produced in the cell by electrolysis of an electrolyte containing a soluble metal salt. Preferably,

a diaphragm cell is used so that the electrolyte comprises an anolyte' and a catholyte disposed respectively adjacent anode andcathode.

In such operations, the high production rates required in practical operation make it necessary to use high current densities at the cathode, curin that'it tends to destroy rent densities of the order of 35 amperes or more per 100 square centimeters of cathode area for example.

Unless special precautions are taken, however, the use of such high current densities tends to involve the liberation of hydrogen as hydrogen in substantial proportions. Such liberation of hydrogen impairs the eiliciency of the operation in two respects, it is in itself a direct loss and it involves an additional indirect loss generated hydrogen peroxide by reduction.

I have found that, when using high current densities, important improvements in efllciency are attained by maintaining the catholyte sub- 85 stantially saturated with respect to oxygen. In

this manner I am able to suppress the liberation of hydrogen as such and thus to reduce, or avoid, loss by decomposition of hydrogen peroxide generated as well as the direct loss of hydrogen.

40 The overall improvement to be attained by application of my invention in connection with the use of high current densities may be remarkable because of this two-fold character.

- In carrying out my invention, saturation of the catholyte may be effected and maintained within the cell proper or in a separate saturator through which catholyte is circulated from and to the cell. For example, the partial pressure of oxygen in the atmosphere to which the catho- 50 lyte is exposed in the cell may be increased by increasing the concentration of oxygen in this atmosphere, by addition of oxygen as oxygen for example, to eifect such saturation. Again for example, oxygen or a gas mixture rich in oxygen 55 may be forced through or into the catholyte,

under the pressure prevailing in the cell or better mental hydrogen is decreased.

under a somewhat higher pressure, in a separate saturator through which catholyte is circulated from and to the cell to effect such saturation.

In some applications of my invention, the operation may be conducted without substantial liberation of hydrogen as such and, consequently, without substantial impairment of efllciency from this cause.

I claim: 1. In a process involving the production of hydrogen peroxide in a diaphragm cell by a recathodic hydrogen produced by electrolysis of an electrolyte comprising an anolyte and a catholyte containing a soluble metal salt, the improvement which comprises impressing across the cell a current of a density of at least 35 amperes per 100 square centimeters of cathode area, and niain- I taining the catholyte substantially saturated with respect to oxygen, whereby the elimination of elemental hydrogen is inhibited and the production rate .of hydrogen peroxide in the cell is increased.

In a process involving the production of hydrogen peroxide in a diaphragm cell by a reaction between oxygen absorbed at a cathode containing activated carbon and cathodic hydrogen produced by electrolysis of an electrolyte comprising an anolyte and a catholyte containing a soluble metal salt, the improvement which comprises impressing across the cell a current of a density of at least 35 amperes per 100 square centimeters of cathode area, removing the catholyte from the cell, saturating the catholyte with oxygen outside the cell, and returning the saturated catholyte to the cell, whereby the production of elemental hydrogen is inhibited and the production rate of hydrogen peroxide in the cell is increased.-

3. In a process involving the production oi hydrogen peroxide in a diaphragm cell by reacting oxygen absorbed at a cathode containing activated carbon with cathodic hydrogen produced by electrolysis of an electrolyte comprising an anolyte and a catholyte containing a soluble metal salt, the improvement which comprises impressing across the cell a current of a density of at least 35 amperes per 100 square centimeters. circulating the catholyte to and from the cell through a separate saturator, and saturating the catholyte with oxygen in the saturator at a pressure in excess of the pressure in the cell, whereby the production of hydrogen peroxide at the cathode is increased and the production of ele- ERNBTBERL.

, action between oxygen absorbed at a cathode and 

